Can a curve object modifier created geometry be used as boolean factor
As you have guessed blender doesn't let you use a curve object for boolean operations. While the remesh modifier technically turns the result into a mesh, it is still a curve based object.

I think your best option is to duplicate the text &#8679; ShiftD, then &#9095; AltC to convert the duplicate to a mesh and use it for the boolean. As you leave the original text object you can delete the mesh text, alter the text and repeat.